Yang Chunlei, Lan Wei, Ye Shijie, Zhu Binna, Fu Zhengwei
College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China.
College of Animal Sciences, Zhejiang University, Hangzhou, China.
Front Physiol. 2020 Oct 29;11:588082. doi: 10.3389/fphys.2020.588082. eCollection 2020.
The ruminal epithelium is continuously challenged by antigens released by the lysis of dead microbial cells within the rumen. However, the innate immune system of the ruminal epithelium can almost always actively respond to these challenges. The cross talk between the ruminal microbiota and innate immune cells in the ruminal epithelium has been suggested to play an important role in sustaining the balance of immune tolerance and inflammatory response in the rumen. We hypothesized that conjugated linoleic acid (CLA), a functional microbial metabolite in the rumen, may contribute to the immune regulation in rumen epithelial cells (RECs); therefore, we first established an immortal REC line and then investigated the regulatory effects of CLA on the immune responses in these RECs. The results showed that long-term REC cultures were successfully established via SV40T-induced immortalization. Transcriptome analysis showed that a 100 μM CLA mixture consisting of 50:50 -9, -11:-10, -12 CLA significantly downregulated the expression of the inflammatory response-related genes TNF-α, IL-6, CX3CL1, IRF1, ICAM1 and EDN1, and upregulated the expression of the cell proliferation-related genes FGF7, FGF21, EREG, AREG and HBEGF and the lipid metabolism-related genes PLIN2, CPT1A, ANGPTL4, ABHD5 and SREBF1 in the RECs upon LPS stimulation. Correspondingly, the GO terms regulation of cell adhesion, response to stimulus and cytokine production and KEGG pathways TNF and HIF-1 signaling, ECM-receptor interaction and cell adhesion molecules were identified for the significantly downregulated genes, while the GO terms epithelial cell proliferation and regulation of epithelial cell migration and the KEGG pathways PPAR, ErbB and adipocytokine signaling were identified for the RECs with significantly upregulated CLA-pretreated genes upon LPS stimulation. These findings revealed that CLA conferred protective immunity onto the RECs by inhibiting proinflammatory processes, promoting cell proliferation and regulating lipid metabolism related to the immune response.
瘤胃上皮不断受到瘤胃内死亡微生物细胞裂解所释放抗原的挑战。然而，瘤胃上皮的固有免疫系统几乎总能积极应对这些挑战。瘤胃微生物群与瘤胃上皮固有免疫细胞之间的相互作用被认为在维持瘤胃免疫耐受和炎症反应平衡中起重要作用。我们假设瘤胃中的一种功能性微生物代谢产物共轭亚油酸（CLA）可能有助于瘤胃上皮细胞（RECs）的免疫调节；因此，我们首先建立了一个永生化的REC系，然后研究了CLA对这些RECs免疫反应的调节作用。结果表明，通过SV40T诱导永生化成功建立了长期的REC培养物。转录组分析表明，由50:50 -9, -11:-10, -12 CLA组成的100 μM CLA混合物在LPS刺激下显著下调了炎症反应相关基因TNF-α、IL-6、CX3CL1、IRF1、ICAM1和EDN1的表达，并上调了细胞增殖相关基因FGF7、FGF21、EREG、AREG和HBEGF以及脂质代谢相关基因PLIN2、CPT1A、ANGPTL4、ABHD5和SREBF1在RECs中的表达。相应地，对于显著下调的基因，鉴定出细胞黏附调节、对刺激的反应和细胞因子产生的GO术语以及KEGG途径TNF和HIF-1信号传导、ECM-受体相互作用和细胞黏附分子，而对于LPS刺激下CLA预处理基因显著上调的RECs，鉴定出上皮细胞增殖和上皮细胞迁移调节的GO术语以及KEGG途径PPAR、ErbB和脂肪细胞因子信号传导。这些发现表明，CLA通过抑制促炎过程、促进细胞增殖和调节与免疫反应相关的脂质代谢，赋予RECs保护性免疫。
